ISO K — Cast Iron · K30
K30 — Malleable iron
Hardness range: 150–230 HB. Part of the ISO K — Cast Iron group. Cast iron is abrasive and brittle — short chips, no built-up-edge. CVD alumina (Al₂O₃) coatings resist the high-temperature abrasion. Dry machining is acceptable for grey iron; coolant helps with nodular grades. Main failure mode: flank wear. High-speed machining is effective.
Material profile — K30
- ISO designation
- K30 (ISO K — Cast Iron)
- Material
- Malleable iron
- Hardness
- 150–230 HB
- ISO group colour
- Cast Iron
Tooling guidance — K-group
- Group summary
- CVD alumina coatings excel. Dry machining acceptable for grey CI. Abrasive wear is the main failure mode.
Insert selection for malleable iron — starting point
- ISO application class
- K (cast iron). Malleable iron sits between grey and ductile iron; it has some ductility, so a slightly tougher edge than a grey-iron grade helps. Match the ISO K class across brands rather than the brand name (Sandvik, Kennametal, Iscar, Walter, Seco and Mitsubishi each publish one), then confirm the exact grade for your condition.
- Grade & coating
- CVD-coated carbide, K10–K20. A little tougher than a pure grey-iron grade because malleable iron is more ductile.
- Geometry
- Negative geometry, honed edge for skin and interruptions. Mostly short chips.
- Starting parameters
- Vc ≈ 120–250 m/min, fn ≈ 0.10–0.40 mm/rev, dry or with coolant. Confirm in the advisor or on a sample part.
Selection table: malleable iron
| Operation | Geometry | ISO class | Coating family | Coolant | First check |
|---|---|---|---|---|---|
| Roughing | Negative geometry, honed edge for skin | K10–K20 | CVD-coated carbide, a little tougher than a grey-iron grade | Dry or with coolant | Abrasive flank wear: sensible speed |
| Finishing | Negative geometry; mostly short chips | K10–K20 | CVD-coated carbide | Dry or with coolant | Mild built-up edge at low speed: raise the speed |
| Interrupted cut | Honed edge for skin and interruptions | K10–K20 (tougher end) | Tougher CVD-coated carbide | Dry or with coolant | Chipping on cast skin: ease into the cut |
| Low rigidity / thin wall | Negative geometry with honed edge; support the part | K10–K20 | CVD-coated carbide | Dry or with coolant | Frittering at exit: reduce feed at exit |
malleable iron: what goes wrong, and what to check first
- Abrasive flank wear
- Use a CVD-coated K-grade and a sensible speed.
- Mild built-up edge at low speed
- More ductile than grey iron, so it can build up at low speed. Raise the speed into the band.
- Edge chipping on cast skin
- Use a tougher grade with a honed edge and ease into the cut.
- Frittering at exit
- Reduce feed at exit or use a tougher grade.
Reference data
Frequently asked questions
What insert grade for malleable iron?
A CVD-coated carbide, K10–K20, slightly tougher than a grey-iron grade because malleable iron is more ductile. Match the ISO K class across brands and confirm in the advisor.
How does malleable iron differ from grey iron to machine?
It is more ductile, so it can form a mild built-up edge at low speed and benefits from a slightly tougher edge.
What cutting speed for malleable iron?
Roughly Vc 120–250 m/min, fn 0.10–0.40 mm/rev. Confirm on a sample part.
Why do I get built-up edge on malleable iron?
Its ductility lets it build up at low speed; raise the speed into the working band.
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